Methods of forming capacitor constructions

ABSTRACT

The invention includes a method of treating a predominantly inorganic dielectric material on a semiconductor wafer. A laser is utilized to generate activated oxygen species. Such activated oxygen species react with a component of the dielectric material to increase an oxygen content of the dielectric material. The invention also includes a method of forming a capacitor construction. A first capacitor electrode is formed to be supported by a semiconductor substrate. A dielectric material is formed over the first capacitor electrode. A precursor is provided at a location proximate the dielectric material, and a laser beam is focused at such location. The laser beam generates an activated oxygen species from the precursor. The activated oxygen species contacts the dielectric material. Subsequently, a second capacitor electrode is formed over the dielectric material.

RELATED PATENT DATA

This patent resulted from a divisional application of U.S. patentapplication Ser. No. 10/222,330, which was filed on Aug. 15, 2002, whichwas a continuation application of U.S. patent application Ser. No.09/945,308 which was filed on Aug. 30, 2001 Pat. No. 6,573,199.

TECHNICAL FIELD

The invention pertains to methods of treating dielectric materials withoxygen, and in particular embodiments pertains to methods of formingcapacitor constructions.

BACKGROUND OF THE INVENTION

Dielectric materials are incorporated into numerous semiconductorconstructions, including, for example, capacitor constructions. Thedielectric materials will frequently comprise an oxide, such as, forexample, one or more of silicon dioxide, silicon oxynitride, andtantalum pentoxide. A difficulty that can occur in forming suchdielectric materials is that there can be regions within the materialswhich are oxygen deficient. For instance, there can be regions within atantalum pentoxide material in which the ratio of tantalum to oxygen ishigher than that which exists in the stoichiometric material Ta₂O₅. Suchregions have a lower dielectric constant than would exist if the regionshad sufficient oxygen to reach the stoichiometry of Ta₂O₅.

It is typical for a dielectric material to comprise oxygen-deficientregions interspersed within a material that predominantly is not oxygendeficient. For instance, it is common for Ta₂O₅ to be formed underconditions in which the majority of the material comprises thestoichiometry of Ta₂O₅, and in which oxygen-deficient regions areinterspersed throughout the tantalum pentoxide material. Theoxygen-deficient regions can disrupt a uniformity of the physicalproperties of the tantalum pentoxide material. For instance, theoxygen-deficient regions can disrupt the uniformity of dielectricstrength throughout the tantalum pentoxide material. Disruption of thephysical properties of the tantalum pentoxide material can causeinconsistencies in device performance from semiconductor devicesincorporating the dielectric material, which can reduce performance ofthe devices and, in particularly problematic cases, can render thedevices inoperable.

A solution to the problem of having oxygen-deficient regions within adielectric material is to expose the material to an oxidant to cureoxygen deficiencies within the material. For instance, dielectricmaterials can be exposed to ozone to cure oxygen deficiencies within thematerials. A difficulty which is frequently encountered is that theoxidants do not cure enough of the oxygen deficiencies within adielectric material to acceptably overcome the above-described problemsassociated with having oxygen deficiencies interspersed throughout adielectric material. Accordingly, it would be desirable to develop newmethods for reducing the oxygen deficiencies within a dielectricmaterial, and it would be particularly desirable if such methods couldentirely eliminate oxygen deficiencies throughout a dielectric material.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a method of treating apredominantly inorganic dielectric material on a semiconductor wafer. Alaser is utilized to generate activated oxygen species. Such activatedoxygen species react with a component of the dielectric material toincrease an oxygen content of the dielectric material.

In another aspect, the invention encompasses a method of forming acapacitor construction. A first capacitor electrode is formed to besupported by a semiconductor substrate. A dielectric material is formedover the first capacitor electrode. A precursor is provided at alocation proximate the dielectric material, and a laser beam is focusedat such location. The laser beam generates an activated oxygen speciesfrom the precursor. The activated oxygen species contacts the dielectricmaterial. Subsequently, a second capacitor electrode is formed over thedielectric material.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic, cross-sectional view of an apparatusconfigured for treatment of a dielectric material in accordance with amethod of the present invention.

FIG. 2 is a diagrammatic top view of a semiconductor wafer treated inaccordance with a method of the present invention.

FIG. 3 is a diagrammatic cross-sectional side view of a semiconductorwafer fragment treated in accordance with a method of the presentinvention.

FIG. 4 is a view of the FIG. 3 wafer fragment shown at a processing stepsubsequent to that of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention includes methods of treating dielectric materials withactivated oxygen species. The activated oxygen species can be formed byimpacting an oxygen-containing material with a laser beam to change anelectronic state of an oxygen component of the material, and therebygenerate the activated oxygen species from such oxygen component. Theactivated oxygen species generated by the laser beam can interact withoxygen-deficient regions of the dielectric material to increase anoxygen content of such material. For instance, the activated oxygenspecies can directly react with components of the dielectric materialassociated with an oxygen-deficient region to bond with such components,and thereby increase an oxygen content of an otherwise oxygen-deficientregion of the dielectric material.

Although methodology of the present invention can be utilized fortreating any dielectric material, the methodology can offer particularadvantages when utilized to treat predominantly inorganic dielectricmaterials. The term “predominantly inorganic” is used to indicate thatless than 50 weight percent of the dielectric material is carbon.Typically, less than 10 weight percent of the material will be carbon.For instance, the dielectric material can comprise one or more oftantalum pentoxide, aluminum oxide, hafnium oxide, titanium oxide,strontium titanate, barium strontium titanate (BST) and siliconoxynitride. If the dielectric material is formed by chemical vapordeposition there can be a minor amount of carbon within the material dueto incorporation of a small amount of carbon-containing components ofchemical vapor deposition precursors into the dielectric materials.However, the amount of carbon within the dielectric material willtypically be less than 10 weight percent, frequently less than 5 weightpercent, and often even less than 1 weight percent.

An exemplary method of the present invention is described with referenceto FIGS. 1-4. Referring initially to FIG. 1, an apparatus 10 configuredfor treatment of a semiconductor substrate is illustrated. Apparatus 10comprises a chamber 12 having a window 14 extending therein. Window 14can comprise, for example, quartz.

Chamber 12 further comprises an inlet port 16 and an outlet port 18. Afluid 20 is flowed from a source 21 into chamber 12 through inlet port16, and exits chamber 12 through outlet port 18. Fluid 20 comprises anoxygen-containing component. In particular embodiments, fluid 20 cancomprise a gas, which includes, consists of, or consists essentially ofozone (O₃). The amount of ozone within fluid 20 can vary from about 0.1%concentration (by volume) to about 100% concentration. The ozone can bediluted in a second gas, such as, for example, O₂.

A support structure 22 is provided within chamber 12, and asemiconductor substrate 24 is provided to be supported by supportstructure 22. Support structure 22 can be referred to as a wafer holder.Support structure 22 can comprise components for temperature control ofwafer 24 during processing of the present invention. Such components caninclude one or both of a heating component and a cooling component. Inparticular embodiments, wafer 24 will be heated during processing of thepresent invention, and accordingly support 22 will comprise heatingcomponents (not shown) which maintain wafer 24 at a desired temperature.

Wafer 24 has a dielectric material 26 provided over a surface thereof.Dielectric material 26 can comprise, for example, a predominantly inorganic dielectric material, such as silicon oxynitride and/or tantalumpentoxide.

Wafer 24 can be referred to herein as a semiconductor substrate.Alternatively, wafer 24 and dielectric material 26 can together bereferred to as a semiconductor substrate. To aid in interpretation ofthe claims that follow, the terms “semiconductive substrate” and“semiconductor substrate” are defined to mean any constructioncomprising semiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials thereon), and semiconductivematerial layers (either alone or in assemblies comprising othermaterials). The term “substrate” refers to any supporting structure,including, but not limited to, the semiconductive substrates describedabove.

A laser beam 30 (illustrated by two arrows, but it is to be understoodthat the arrows can correspond to components of a single laser beam) isgenerated by a source 32 and directed into an optical array. Opticalarray 34 typically comprises focusing lenses (not shown) and one or moremirrors 36 (only one of which is shown). The mirrors 36 direct laserbeam 30. through window 14, and toward a location proximate a surface ofdielectric material 26. Laser beam 30 interacts with anoxygen-containing component of fluid 20 to generate an activated oxygenspecies. Such activated oxygen species can then react with dielectricmaterial 26 to cure oxygen deficiencies within such material.

Laser be am 30 can predominantly comprise a single wavelength of light,and such wavelength can be chosen to interact with a specificoxygen-containing component of fluid 20. For instance, if fluid 20comprises ozone, then laser beam 30 can comprise light having awavelength of from 193 nm to 248 nm. Such light interacts with the ozoneto generate an activated oxygen species. For instance, energy from thelaser beam can cause O₃ to break down into an activated oxygen componentand a diatomic oxygen component (O₂). The laser beam can be specificallychosen to interact only with specific oxygen-containing components offluid 20, and not with other components. For instance, if fluid 20comprises a mixture of O₃ and O₂, the laser beam wavelength(s) can bechosen such that the laser beam light interacts only with the O₃.

It can be desired to carefully control a concentration of laser-lightabsorbing materials within reaction chamber 12. For instance, if alaser-light absorbing material is O₃ it can be desired to control anamount of O₃ within reaction chamber 12. Specifically, if an amount ofO₃ within the chamber is too high, the laser energy will be absorbed bythe O₃ before the laser beam 30 has penetrated a sufficient distancewithin chamber 12 to reach a desired location proximate dielectricmaterial 26. On the other hand, if the concentration of O₃ is too low,there will not be a sufficiently high flux of reactive oxygen speciesdelivered proximate dielectric material 26 to react with the variousoxygen-deficient regions within the dielectric material 26. In anexemplary method of the present invention, fluid 20 comprises a gaseousmixture of O₃ and O₂, with the O₃ being present to a concentration ofabout 1%-10% (by volume), and the mixture being flowed through chamber12 at a rate of about 1000 standard cubic centimeters per minute (sccm).A distance from an upper surface of dielectric material 26 to window 14is about 25 millimeters, and the laser beam 30 is focused at a locationthat is from about 2 millimeters to about 4 millimeters above an uppersurface of dielectric material 26. Wafer 24 is heated to a temperatureof about 300° C. during such exemplary processing.

Referring to FIG. 2, wafer 24 is illustrated in a top view to illustratea location of laser beam 30 relative to an upper surface of dielectricmaterial 26. Wafer 24 comprises a first edge 50 and an opposing secondedge 52. Further, wafer 24 comprises a center 54 between edges 50 and52. A distance 56 extends between edges 50 and 52, and across the center54. In the shown preferred embodiment, laser 30 comprises a band whichextends across a majority of the distance between edges 50 and 52, andspecifically which extends across an entirety of the distance betweenedges 50 and 52. Band 30 is preferably passed across a surface of wafer24 during processing of the present invention. An axis 58 is provided toshow an exemplary direction along which band 30 can be passed relativeto wafer 24 so that band 30 will ultimately pass across an entirety ofwafer 24. The passing of band 30 relative to wafer 24 can beaccomplished by moving one or both of wafer 24 or the laser beamcorresponding to band 30. FIG. 1 describes an exemplary embodimentwherein wafer 24 is configured to be held stationary while laser beam 30is passed across a surface of wafer 24. Specifically, the mirrorassembly 36 can be moved along axis 58 to cause laser beam 30 totraverse along an entirety of the surface of wafer 24.

Although laser beam 30 is described as preferably being in theconfiguration of a long narrow band in the embodiment of FIGS. 1 and 2,it is to be understood that laser beam 30 can comprise other shapes,such as, for example, a circular beam which is traversed along the shownaxis 58, and along another axis orthogonal to the shown axis (forinstance, axis 58 can be considered to be a “X” axis, and the orthogonalaxis would be a “Y” axis extending into and out of the page of FIG. 1)to traverse across an entirety of the upper surface of the wafer.Alternatively, the beam can be configured to be wide enough to cover anentirety of the surface of wafer 24 without being passed across suchsurface.

FIGS. 3 and 4 illustrate an expanded view of a semiconductor waferconstruction treated in accordance with methodology of the presentinvention.

Referring first to FIG. 3, such illustrates a wafer fragment 60comprising a substrate 62. Substrate 62 can comprise a semiconductivematerial, such as, for example, monocrystalline silicon. Further,substrate 62 can comprise a stack of materials, such as, for example, astack comprising an insulative material over various conductive andsemiconductive materials.

Conductive blocks 64 are illustrated over substrate 62. Blocks 64 cancomprise conductively-doped silicon and/or metal.

A dielectric material 66 is shown over substrate 62 and blocks 64.Dielectric material 66 comprises a first layer 68 and a second layer 70.First layer 68 can comprise silicon dioxide, silicon nitride, and/orsilicon oxynitride. In particular embodiments, layer 68 comprisessilicon oxynitride, and specifically comprises regions having thestoichiometry Si_(x)O_(y)N_(z), wherein X, Y and Z are all greater than0. Further, mass 68 has a ratio of silicon to oxygen within at leastportions of the mass which correspond to regions which are oxygendeficient relative to a desired ratio of silicon to oxygen within suchportions of the mass.

Layer 70 comprises a metal and oxygen, and in particular embodimentscomprises tantalum and oxygen. Layer 70 can, in particular embodiments,comprise tantalum pentoxide having oxygen-deficient regions therein.

Fluid 20 is illustrated being flowed across a surface of dielectricmaterial 70, and laser beam 30 is shown focused at a location 72 withinfluid 20. An activated species 74 is generated within fluid 20 at thelocation 72. Activated species 74 can comprise, for example, anactivated oxygen species. The activated species 24 can migrate fromlocation 72 to the dielectric material 70, as indicated by arrow 76.

Once the activated species 74 reaches dielectric material 70, it canreact with a component of dielectric material 70 (such as a metalcomponent of a metal oxide) to form a bond to such component Theactivated species can thereby increase a concentration of oxygen withinthe dielectric material to alleviate or cure an oxygen deficiency withinsuch material. For instance, if material 70 comprises tantalum andoxygen, an activated oxygen species can react with the tantalum ofoxygen-deficient regions to cure an oxygen deficiency within material70.

It is noted that laser beam 30 can generate more than one activatedspecies within a fluid 20, depending on the composition of the fluid,and also depending on the particular wavelength(s) of light present inthe laser beam. If multiple activated species are generated, one or moreof such species will preferably be capable of reacting with a componentof dielectric material 70 and/or dielectric material 68 to increase adielectric constant of at least a portion of the materials. Theactivated species can additionally, or alternatively, react with thecomponent of dielectric material 70 and/or dielectric material 68 toreduce a leakage of current through one or both of materials 68 and 70.Reduction of leakage current can improve capacitive properties ofconstructions comprising materials 68 and 70.

In embodiments in which layer 68 comprises Si_(x)O_(y)N_(z), anactivated oxygen species 74 can migrate through material 70 to reactwith the silicon of the Si_(x)O_(y)N_(z) to thereby decrease a ratio ofsilicon to oxygen within the material 68.

In one aspect, the interaction of activated species 74 with one or bothof dielectric materials 68 and 70 can be considered to be interaction ofan activated oxygen species with portions of either material 68 or 70that are not fully oxidized, to increase an amount of oxidation of suchportions.

In the shown embodiment, a focal point of laser beam 30 is above anuppermost surface of wafer fragment 60. Preferably, the focal point oflaser 30 is a distance of from about 2 millimeters to about 4millimeters above a surface of fragment 60 as the laser beam is passedacross such surface. The distance of from about 2 millimeters to about 4millimeters is close enough that activated species can migrate to thedielectric material associated with a surface of fragment 60, and yetfar enough that the focal point of the laser beam does not inadvertentlyimpact a surface of the dielectric material.

An advantage of methodology of the present invention is that suchgenerates a high flux of activated species proximate a surface of adielectric material which is to be treated with such activated species.Another advantage is that the laser beam is utilized to generateactivated species, rather than being utilized to directly impact thedielectric material. In other words, the laser light is utilized togenerate a migratory reactive species, rather than being directlyutilized in any reaction occurring within dielectric material 70.Accordingly, the laser light can be focused at varying locationsrelative to dielectric material 70, and yet the migratory reactivespecies will traverse to the dielectric material and react therewith. Incontrast, if the laser light were utilized directly in a reaction withthe dielectric material, a focal point of the laser light wouldtypically be directed at a surface of the dielectric material. Such canbe problematic in applications, such as that shown, in which thedielectric material has an undulating upper surface, as it can bedifficult to keep the laser beam focused on such undulating surface asthe laser beam is passed across the surface. Another problem can occurin the difficulty of hitting vertical walls or surfaces with the laserenergy. However, methodology of the present invention is simplifiedrelative to processes in which a laser beam is focused at a surface ofthe dielectric material in that the present invention can utilize alaser beam which is focused within a range of locations above a surfaceof the dielectric material. It is to be understood, however, that theinvention can also encompass embodiments wherein the laser beam isfocused at the surface of the dielectric material and generates thereactive species against such surface, but such embodiments aregenerally less preferred than embodiments in which the laser beam isfocused at a location above the surface of the dielectric material.

Referring next to FIG. 4, a conductive material 80 is formed overdielectric material 70. Conductive material 80 can comprise, forexample, one or both of conductively-doped silicon and metal. Conductivematerial 80 and conductive material 64 define capacitor electrodes ofspaced capacitor constructions 82, 84 and 86. Such capacitors comprisecapacitor electrode 80 separated from capacitor electrode 64 byintervening dielectric material 66. The capacitor constructions can beincorporated into semiconductor devices. For instance, the capacitorconstructions can be incorporated into dynamic random access (DRAM)devices by coupling the capacitor constructions with transistor gates(not shown) to form DRAM cells.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A method of forming a capacitor constructioncomprising: forming a capacitor electrode supported by a semiconductorsubstrate; forming an oxide material over the capacitor electrode, theoxide material having oxygen-deficient regions therein; providing aprecursor proximate the oxide material; focusing a laser beam at adistance of from about 2 mm to about 4 mm above a surface of the oxidematerial, the laser beam generating an activated oxygen species from theprecursor; and contacting the oxide material with the activated oxygenspecies to at least partially reduce the oxygen deficiency within theoxygen-deficient regions.
 2. The method of claim 1 wherein the oxidematerial comprises silicon and wherein the activated oxygen speciesreacts with the silicon.
 3. The method of claim 1 wherein the oxidematerial comprises at least one metal selected form the group consistingof hafnium, aluminum, barium, strontium, titanium, and tantalum.
 4. Themethod of claim 1 wherein the providing the precursor comprises flowinga fluid comprising ozone into a reaction chamber containing thesubstrate.
 5. The method of claim 1 wherein the substrate comprises atemperature of about 300° C. during the contacting.
 6. The method ofclaim 1 wherein the laser beam is scanned across the surface and whereinthe focal point of the laser beam does not impact the surface during thescanning.